Powertrain, generic (extended)

P2687 Fuel Supply Heater Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

Diesel engines warm the fuel at the filter so that wax crystals do not block it in frost. P2687 says the control line of that heater is open. In GM's diesel ECM tables the engine computer switches the heater relay with a low-side driver and judges the off-state voltage; more than 200 kOhm between pin and ground means open. The 2014 version (14OBDG04) needed 11 V for 3 s and 2 s of fault, Type B with MIL; the 2017 and 2020 versions use 10 bad readings out of 20 at 100 ms and rate it Type C without lamp. Ford used the same code differently: its 2015 and 2016 diesel summaries apply P2687 to the vaporizer glow plug of the 3.2 L Transit's downstream injection, open if the line sits at 2.9 to 3.2 V for 5 s; from 2017 that fault moved to P269B.

Likely causes

Heater relay coil open or relay not seated
Broken control wire or corroded terminal at the filter housing
Heater element open where it is switched directly without a relay

Symptoms

  • Hard starting or stalling in severe cold
  • Power loss from a waxed fuel filter
  • Often no warning lamp, depending on model year

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–300
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel supply heaterheater relaywiring harness

Related codes

P2688P2689P269B

References: gsi.ext.gm.com, gsi.ext.gm.com, fordservicecontent.com, fordservicecontent.com.